Metastatic Neuroblastoma Arising in an Ovarian Immature Teratoma in a 16-Year-Old Female: A Case Report.

Background: Neuroblastoma arising within an ovarian immature teratoma is exceptionally rare, with only three prior cases reported and only one in a pediatric patient. Patient: We describe a 16-year-old female with a large ovarian mass. Histopathologic evaluation showed an immature teratoma containing tissues from all three germ layers with immature neuroepithelium. A distinct primitive cell population was noted with findings supporting a diagnosis of poorly differentiated neuroblastoma arising within the teratoma. Extraovarian involvement was identified on peritoneal surfaces and in a regional lymph node. Tumor genetic analysis demonstrated 17q gain, consistent with higher-risk neuroblastoma. She initially received bleomycin, cisplatin, and etoposide per AGCT1531 before transitioning to intermediate-risk neuroblastoma therapy per ANBL0531. Post-treatment imaging showed no definitive recurrent disease, and she remains under surveillance. Conclusions: This case highlights a rare pediatric example of neuroblastoma arising within an ovarian immature teratoma with extraovarian involvement, offering clinically relevant diagnostic, pathologic, and therapeutic insights.